Telephone switching system



June 15, 1965 c. G. MILLER TELEPHONE SWITCHING SYSTEM 7 Sheets-Sheet 1Filed Feb. 2, 1962 June 15, 1965 c. G. MILLER TELEPHONE swITcHINe SYSTEM7 Sheets-Sheet 2 Filed Feb. 2, 1962 INVENTOR.

Charles G.Mi|ler BY a )5MM MIM/7L ATTORNEYS NO ON 7 Sheets-Sheet. 3

Filed Feb. 2, 1962 7 Sheets-Sheet 4 C. G. MILLER TELEPHONE SWITCHINGSYSTEM Lllr June 15, 1965 Filed Feb. 2, 1962 June 15, 1965 c. G. MILLERTELEPHONE SWITCHING SYSTEM 7 Sheets-Sheet 5 Filed Feb. 2, 1962 mmmmOPOmZ ZOO mDJwZdE.

mmm m-m Ohd mmm

BY Charles G Mlller Imm mmm mmxw mmQOOmQ ZZOU mmQOOMD MATTQRNgYsTELEPHONE SWITCHING SYSTEM Filed Feb. 2, 1962 7 Sheets-Sheet 6 FIG. 6

SPECIAL TERMINATING TRUNK To I ocAI. swITcI-IING EQUIPMENT SPECIAL REGISTER LINK 7.o INVENTOR. 7" charles G. Miller M4-v 7%? ATTORNEYS June l5,1965 c. G. MILLER 3,189,687

` TELEPHON SWITCHINGl SYSTEM Filed-Feb. 2,1962 7 sheets-sheet 7 UnitedStates Patent O sneaks? TELEPHNE SWHCHING SYSTEM Charles G. Miiier, S1Aubrey Road, Upper Mont-cian, NJ. Fiied Feb. 2, 1962, Ser. No. 170,635 6Ciairns. (Cl. 179-18) lThis invention relates to telephone systems .andmore particularly to means for preventing the establishment ofunauthorized calls.

With the increased use of telephone switching networks forinterconnecting data processing equipment and tor interconnectingmilitary 'bases it becomes desirable that connections between callingstations and called stations be set up over the regular switchingnetwork, with protection against unauthorized calls, rather than overprivate networks. While such connections may, of course, be establishedunder the control of dialed or keyed designations, there is always thepossibility that unauthorized connections to the important calledstations may be set up either accidentally, or maliciously by dialing orkeying the designations of such stations.

This invention provides for interconnecting `an originating station with.a terminating station via a regular commerci-al telephone switchednetwork, with protection against unauthorized station selection, eitherlaccidental or malicious.v

.It provides for the following features:

(a) Automatic identification of the calling station number via `apassive electrical network.

(b) Transmitting this idcntilication to a tandem switching ofiice, whereit is he-ld until a directive signal is received from the .termin-atingswitching otlice to forward this identity to this terminating switchingoiice.

`(c) In the advancement of a data call, to generate at the originatingtandem point ran extra .and distinctive multifrequency signal which itforwards through the switch train to the switching oiiice just beforethe terminating office and causes .this otlice to con-trol the entryinto the terminating otiice via a separate group of trunks to cause theselection of a new type of incoming register .and associ-ated translatorwith features called for in this invention.

(d) On receipt of the called number, to generate a sign-a1 to the tandemotiice at which the ident-ined calling number is held in order to directthis tandem oiiice to forward the calling number identity to theterminating office.

(e) At the terminating otiice, .a translator which matches the identityreceived with one or more recorded identities `associated with theparticular called number.

(f) At the terminating otiice, withholding the completion to the -callednumber unless the calling number match indicates that the originatingstation is authorized to reach the particular called num-ber.

These and other features of the invention will be more clearlyunderstood from a consideration of the following description, read inconnection with the accompanying drawings, in which* FIGS. 1 .and 2 area schematic showing of the system `as a whole;

FIG. 3 shows a special trunk incoming to -a tandem oice;

FIG. 4 shows a special tandem sender;

FIG. 5 shows equipment at -an intermediate toll oiiice;

lFIG. 6 shows a special trunk incoming to a terminating oice; and

FIG. 7 shows a special incoming register at the terminating oice.

Referring first to FiGS. 1 and 2, two subscriber substations are shown,of which substation 14E@ represents ice an ordinary telephone, whilesubstation 101 represents a subst-ation equipped with a data sendingunit. Both Vsubst-ations are connected to local switching equipment 1&2,which is controlled by common control equipment 1313. This local oiiiceis also provided with automatic number identifying equipment includingoutgoing trunks 104 and 165, link 106, outpulser 1017, identifier 108,and number network 109. For the purpose of number identiiication, eachsubstation has an individual directory sleeve terminal such as terminals1,10 and 111 which are connected to number network 109. Each subst-ationis also associated, in the local switching equipment, with a classterminal (not shown) which determines the class of service to which thesubstation is entitled. Theretore, when the telephone substation 16)yoriginates `a call to a distant otiice, that subst-ation will beextended to a standard trunk, such as trunk 104, while the data sendingsubstation 161, for a call to a distant oliice, will 'be ext-ended to aspecial trunk, such as trunk 105.

At the tan-dem otice, special senders, such as sender 117 tare used forhandling data sending calls. rTherefore, the standard incoming trunks,such as trunk 112, and the special incoming trunks, such as trunk 115,t0 which data sending calls are routed by the originating ofiice, .arearranged in separate groups. Standard incoming trunk-s use one senderconnector, such as stand- .ard sender connector 113, to reach standardsenders, such as sender 1.14. Special incoming trunks use a similar, butseparate sender connector, identiiied as special sender connector 116,to reach special senders, such 'as sender 117. The stand-ard senders:and the special senders, in establishing connections through the tandemofdce, function in 4a similar manner and employ, in common, standardmarker connectors, such as connector 118 and standard markers, such asmarker 1119. Mar-ker 119 controls the tandem switching equipment 121,obtaining access thereto by means of connectors 12). Both types of callare exten-ded over standard out-going trunks, `such as trunk 122. It maybe .assumed that the tandem oice is provided with centralized automaticmessage account-ing equipment, and that the automatic lineidentiti-cation :equipment at the local oiice transmits the callingstation number to the tandem oice for charging purposes. Since theaccounting operations do not enter into the invention, they have notbeen disclosed. However, in the accounting operations the callingstation identity is cleared when the accounting record h-as been made,but in this invention the calling station identity is Vheld and thetandem sender is held facing the outgoing connection until it recognizesfrom the terminating end a signal requesting the transmission forward ofthe calling identity.

The call may be extended through one or more intermediate toli oiiicessuch as office 20d. These oilices are modified to receive .and transmita special signal generated by the special tandem sender to indicate thata data sending call is bein-g established. Between intermediate ofces,standard interothce trunks are used. When the last intermediate oiiicedetermines that the call is to be directed to the terminating otlice,the special signa'l is not transmitted, but 4a special trunk circuit isselected. if no special sign-al has been received, the intermediateoiiice selects a standard trunk to the terminating oiiice.

At the terminating oioe, the standard trunk, selected by theintermediate oiiice, appears in standard incoming trunk circuit 201,which connects itself, by means of standard incoming register link 202with a standard in- Corning register, such as register 203. Similarly,the special trunk, selected by the intermediate oilice appears in aspecial incoming trunk, such yas trunk 2M, which Lconnector 211.

3 connects itself by means ot special incoming register link 205 with 1aspecial incoming register, such as register 206. Link 205 differs fromlink 202 only in that it serves special trunks .an-d special incomingregis-ters.

Standard incoming register 203 receives the called line number from theintermediate office and at once operates standard marker connector 207to connect with standard marker 20S. Marker 208 functions to locate andtest the called line such as telephone 209, and connects with the trunklink trame 210, in which the incoming trunk 201 appears, by means oftrunk link frame It also connects with line linl; frame 212, in whichthe called link 209 appears by means of line link frame connectors 213,after which it selects an idle channel between trunk 201 and line 209and completes the connection.

The special incoming register 206 also receives the called line numberfrom the intermediate otiice. As each intermediate office completes itsfunctions, it establishes talking and signaling paths therethrough. Gnstandard calls, the tandem office has already extended these talking andsignaling paths to the originating olice. On the special data sendingcalls, forming the subject of the present invention, the special sender117 remains con nected to the outgoing trunk.

Having received the called line num er, special incoming register 206.transmits a signal to the special sender 117, in response to which thespecial sender 117 transmits the calling line number to the incomingregister 206. In the meantime, register 206 has operated specialtranslator connector 214 to connect with a special translator 21S. Theregister 206 then transfers the called line number to the translator,which is wired to set up a registration of the number of the callingline which is privileged to extend calls to the data receiving unit 216.When the calling line number has been received from the tandem otiiceand the translator has operated, the two calling line numbers are set upin matching circuit 217. If the matching circuit indicates that the twocalling line numbers are the same, the register 206 operates markerconnector 207 to connect with marker 208 and the marker proceeds toconnect special incoming trunk 204 with the data receiving unitV 216.Register 206 also transmits a match signal to .the tandem otllce topermit the special sender 117 to release and complete the connectionwith the originating oflice.

If the matching circuit 217 indicates that the two calling line numberspresented to it are not the same, the register is given a troublerelease signal and a no matc signal is transmitted to the tandem sender.The tandem sender then causes a trouble record to be made, after whichthe calling line is given an indication that the call cannot becompleted.

The detailed drawings are based on dial telephone circuits in generaluse. Reference may be made to US. Patent No. 2,848,543, granted to R. N.Breed et al. August 19, 1958, for a typical tandem oiice; to US. PatentNo. 2,868,884, granted to I. W. Gooderham et al. January 13, 1959, for atypical toll office and to U.S. Patent No. 2,585,904 granted to A. J.Busch February 19, 1952, for a typical local oiiice. For details of theautomatic number identification equipment reference may be made to anarticle Vappearing in The Bell System Technical Journal, September 1958,page 1295.

The inventionialso contemplates the possibility of the use ot four-wiretransmission throughout the telephone network as well as other forms otautomatic line number identiiication. Y

When the common control equipment at the originating oiiice has receiveda call from the data sending unit 101 and has registered the number ofthe wanted line, for example that of data receiving unit 216, it willalso receive a class indication. Assuming that the call must be routedthrough the tandem oiiice, the common control equipment will select aspecial trunk outgoing to the back tandem oiice and prepare anoutpulsing circuit over the outgoing conductors of the special trunk.

At the special tandem trunk of FIG. 3, this prepared outpulsing circuitresults in the completion of a circuit from battery, through the upperWinding of relay 304, back Contact ot relay 303, back contact of relay302, trunk conductor 300, through the common control equipment at theoriginating ohce, back to conductor 301, back contact of relay 302, backcontact of relay 303, to ground through the lower winding of relay 304.Relay operates in this circuit and closes a circuit from ground over itsfront contact, back contact of relay 305, contact ot relay 306, backcontact of relay 303 to conductor 307.

With conductor 307 grounded', special sender connector operates toconnect the trunk circuit of FIG. 3 with the tandem sender shown in FIG.4. When connector 300 has operated and certain preliminary functionshave taken place in the sender, relay 400 operates, closing a circuitfrom ground over its front contact, back Contact of relay 401, conductor411, through connector 300, conductor 311, to battery through thewinding of relay 303. Relay 303 operates in this circuit, disconnectingincoming conductor 300 from the winding of relay 304 and extending itover a front contact of relay 303, conductor 313, through connector 305,conductor 413, back contact of relay 402 to the called number receivingand steering circuit 404. Relay 303 also disconnects incoming conductorF301 from the winding of relay 304 and extends it over a front contactof relay 303, conductor 314, through connector 308, conductor 414, backcontact of relay 402 to the called number receiving and steering circuit404. Relay 303 also opens the start circuit for connector 30S, but theconnector is now held from tl e sender.

rl`he transfer of conductor 300 and 301 from the windings ot relay 304Ito the receiving circuit in the sender causes the control equipment 103in the originating ofce to transmit the called line number to thereceiving circuit 404, which operates the called number register 405 inaccordance with the number received.

When the tirst three digits of the called number have been received,usually representing the area code of the area in which the calledoffice is located, relay 406 is operated. Relay 406 causes the operationof the marker connector 407, which connects the marker 408 with thesender. The marker 40S functions in the usual manner to select anavailable route leading toward the wanted otlice, after which it selectsan idle trunk leading to the irst otlice in the selected route andconnects the incoming trunk to the selected trunk. When the marker hascompleted its functions, it operates relay 409, which in turn operatesrelay 420 to prepare the outpulsing circuit.

When the called number has been completely recorded in register 405,relay 421 is operated, in turn operating relay 402. Relay 402disconnects conductors 413 and 414 from receiving circuit 404 andconnects them with the calling number receiving and steering circuit422.

At the originating otlice, the completion of the sending of the callednumber is indicated to truuk 10S. Trunk 105 thereupon operates theautomatic number identification equipment, operating link 106 to connectwith outpulser 107. Outpulser 107 connects with identifier 108, whichsignals the trunk 105 to apply a characteristic tone to the sleeveconductor of the connection leading back to the calling number network.This tone appears on directory sleeve terminal 111, which iscross-connected in accordance with the directory number of the callingstation to the number network 109. The identifier 103 scans the numbernetwork and transmits the number as identitied to the outpulser 107.Where a number of originating ofces are located in the same building,the identiiier is equipped to identify the or'lice in which the callingstation is located and indicates the oiiice identity to the outpulser bya single digit.

When identication is complete, the outpulser transmits the single officedigit and the calling number to the tandem otlice. At the tandem oHice,the oitice digit is received by receiving circuit 422, which steers thesingle oiiice digit to register 423 and the calling number to register424. When connector 30S operated, it transmitted the identity of thetrunk over a group of conductors, indicated by conductor 417 to thetrunk number register 426 in the sender. From the trunk number thebuilding at which the call originated can be determined. The oiceslocated in the building are known, together with the single digitassigned to each oflce for automatic message accounting. Therefore, bysuitable cross-connections controlled by the trunk number register 426and the single digit oflice register 423, the area code and oice codeare set up in the area and olice code registers 425.

When the marker has completed its operation and the connection with theintermediate oice has been completed, relay 439 is operated aspreviously described. Relay 409, in turn, operates relay 420 whichcompletes a trunk test circuit which may be traced from trunk conductor315, through connector 308, conductor 415, front contact of relay 420,lower left Winding of repeating coil 427, through the lower Winding ofpolarized relay 423, which is polarized by a local circuit through itsupper winding, winding of test relay 419, upper left winding ofrepeating coil 427, front contact of relay 420, conductor 416, throughthe connector 368 to trunk conductor 316. The circuits which completethis circuit at the intermediate oiiice have not been shown. If thecircuit is satisfactory, relay 419 operates to prepare the tandem senderfor outpulsing and the equipment at the 4intermediate otice operates thesender link to connect the incoming trunk to the sender. While thesender link is being operated, the intermediate oiice transmits a signalwhich causes relay 428 to close its right contact. A circuit is therebyclosed from ground over the right contact of relay 428, back contact ofrelay 430, to battery through the winding of relay 429. Relay 429operates and locks through the winding of relay 436 to oit-normalground, but relay 430 cannot operate at this time, being shunted by theoperating circuit of relay 429. Relay 429 closes a circuit over itsfront contact and a back contact of relay 431 to prepare the outpulsesteering circuit 432 for operation. It also prepares a circuit foroperatingthe pulse generator 433.

When the sender at the intermediate oihce is ready to receive pulses, itcauses the current ow through the winding of relay 428 to be reversed,so that relay 428 closes its left contact. The ground connected over theleft contact of relay 428 completes a circuit over a back contact ofrelay 434, back contact of relay 435, front contact of relay 429, backcontact of relay 431 to the pulse generator 433, causing the pulsegenerator to start to generate timed pulses which control thetransmission of multifrequency pulses to the intermediate office.

At the start of pulsing, the right winding of repeating coil 427 isconnected over back contacts of relay 438 to two frequency sources inthe multifrequency source 439, which, for convenience may be identied assources 2 and 10. Current from these sources are transmitted through therepeating coil 427 to the Sender at the intermediate ofce as a startsignal, to prepare that sender for receiving the coded pulses.

At the first operation of the pulse generator 433, ground is connectedto conductor 449 and over the back contact of relay 433 to batterythrough the winding of relay 437, causing that relay to operate, lockingthrough the winding of relay 438 to off-normal ground. Relay 438 doesnot operate at this time, since it is shunted by the operating circuitof relay 437.

After an interval, generator 433 removes ground from conductor 440,permitting relay 438 to operate. Relay 438 opens its back contacts,disconnecting the right windings of repeating coil 427 from sources 2and 10 to terminate the start pulse.

Since this tandem sender is particularly designed for the handling ofdata calls, the operation of relay 438 extends the right windings ofrepeating coil 427 over its front contacts, back contacts of relay 431,back contacts of relay 442 to sources 4 and 16 ofthe multifrequencysource 439 as an indication to the intermediate oiiice that it is tohandle a data call.

At the next connection of ground to conductor 44?, a circuit iscompleted over front contact of relay 438, back contact of relay 431,back contact of relay 442 to battery through the winding of relay 441.Relay 441 operates in this circuit and locks through the winding ofrelay 442 to o-normal ground. Relay 442 does not operate until the pulsegenerator 433 removes ground from conductor 440.

When relay 442 operates, conductor 440 is extended over front Contact ofrelay 43S, back contact of relay 431 and front contact of relay 442 tothe outpulse steering circuit 432. Likewise the outpulsing circuitthrough the right windings of repeating coil 427 is extended over frontcontacts of relay 438, back contacts of relay 431 and front contacts ofrelay 442 to the outpulse steering circuit 432. Thereafter, under thecontrol of the pulse generator 433, the outpulse steering circuit 432transmits code pulses representing the called number as registered inregister 405.

When the outpulse steering circuit 432 completes its operation, itoperates relay 443, which in turn operates relay 431, the latter relaylocking to o-normal ground. The operation of relay 431 stops the pulsegenerator and relay 42S holds its left contact closed while theconnection is extended through one or more intermediate otiices.

The showing of an intermediate toll oice in FIG. 5 is largely limited tothe modifications required to permit data calls to be handled.Throughout the toll network, four-wire trunks are used as shown in FIG.5. To connect with two-wire local oces, suitable outgoing trunk circuitsare provided at the local and toll otlices, together with suitablesupervisory signal equipment, none of which have been shown.

When a call is received at the intermediate oice of FIG. 5, the senderlink 500 is operated and relay 561 is operated as described in theabove-identified Gooderham et al. patent. With relay 501 operated,incoming conductors 592 and 503 are extended through condensers Silo and597 and the sender link 560 to the multifrequency receiver 50S. Incomingconductors 504 and 505 are connected together through resistor 509.Outgoing conductors 510, S11, 512 and 513 are extended through senderlink Sti() to hybrid coil 514. The multifrequency pulses incoming overconductors S02 and 533 are received by the receiver 538 and registeredin register 515. When three digits of the wanted number have beenreceived, relay 516 is operated, to in turn operate decoder connector517 and connect an idle decoder S18 with the sender.

As described in connection with the tandem oirice, the called number ispreceded by a start signal and a data signal. The start signal preparesthe receiver 538 for registering coded multifrequency signals, each ofwhich comprises two of the frequencies identitied as frequencies 0, 1,2, 4, and '7 in FIG. 4. Since the data signal does not comprise two ofthe above-mentioned frequencies, no registration is made, but relay 519is operated. For the usual telephone call, relay 519 is, of course, notoperated.

It should be obvious that the data signal referred to could be designedas a secondary start signal which is recognized as identical to theregular start signal by all intermediate otiices in the switch trainexcept the oiice just before the terminating oce. For this latterintermediate oice the secondary start signal is taken both as a startsignal and as a directive to act in a special Way called for in thisinvention. For other intermediate ofices no modications are necessary..This minimizes the cost of introducing to existing systems the featurescalled for in this invention. A As described in theabove-identiedGooderham et al. patent, the selection of an outgoingtrunk is under the vcontrol of a marker 527 which receives itsinstructions from a card translator 526. The decoder 518 selects atranslator and a particular card in accordance with the Y first threeVor the lirst six digits registered.` As previously 519. Two cards willbe provided for each terminating oliice, having data receivingequipment, one of which will be used for telephone calls and the otherfor data calls. Since discrimination is requiredonly for calls going toa terminating oliice, means is also provided for selecting a data cardonly when a terminating call is to be expected. A terminating call maybe expected it the incoming trunk is Vnot of the via-only class, inwhich case relay 52.9 will not be operated by the trunk. In addition,where six digit translation is required, it may result in a terminatingcall. ln Vsuch a case, the first use of the translator will operaterelay 521. With data relay 519 operated and either relay 520non-operated or relay 521 operated, relay 522 is operated. With relay522 non-operated, in the case of a non-data or telephone call or ofanintertoll call, ground isrconnected to conductor 523, and only asingle card need to be provided for the selected route. It relay 522 isoperated, ground is connected to conductor 524 toy select the data cardlof the pair relating to the same oilice.A It, in the case of a sixdigit translation, a terminating oliiice is not reached, the two cards,selected with conductor 523 or 52d grounded, may be identical.

The intermediate office is also arranged to pass the data signal on toother toll oiices, but to omit the data signal when a terminating oiceis'reached. When marker 527l has completed its operation in connectionwith an intertoll call, and thedistant sender is. ready to receive thecalled number designation, relay 525 is operated to prepare theoutpulsing circuit and the pulse generator 529 is started. Theoutpulsing circuit is established when relay 52S is operated andconductors 533 and 534 are connected from the input of the hybrid coil514 over front contacts of relay 52S, back contacts of relay 531 to the2 and 10 sources of multifrequency source 532,

thereby transmitting a start signal to the distance otlice Y through thehybrid coil to conductors 516, Sli, lZ and 513. At the first operationof pulse generator 529, ground is connected to conductor 535, completinga circuit over a back contact of relay 531 to battery through thewinding of relay 539. Relay 536 operates in this circuit and locksthrough the winding oi' relay 531 to ofi-normal ground. Relay 531doesnot operate,-being shunted by the operatingcircuit of relay 53%.When pulse generator 529 removes ground from conductor 535, relay 531operates in the locking circuitV of relay Whether or not a data signalis now transmittedde- .pends on whether or not relay 536 is operated.Relay 536 is operated if an incomingdata signal has been received,rasindicated by the operation of relay 5,19, and the call is being extendedVto another toll otiiceas indicated by the non-operation of Vrelay 537.Relayr537 is operated by the marker when the area code digits and oicecode digits are not to be'transrnitte'd, because the. call has reached aterminating oliice.

With relay 536 operated, as soon as relay 531 operates,

'Y conductor 535 is extended over front-contact of relay Sl, frontcontact of relay 536, back contact of relay 539 to battery through thewinding of relay 538. Y When pulse generator 529 again connectes groundto conductor 35', relay 533 operates and locks through the Winding ofrelay S39 to oit-normal ground, but relay 539 does not operate untilground is removed from conductor 535 at the end of the data pulse. Withrelay 531 operated, the outpulsing circuit extends from hybrid coil 514through the contacts of relay 528, then over front contacts of relay531, front contacts of relay S36 and back contacts or" relay 539 to the4 and 19 sources of multilrequency source 532, thereby transmitting thedatasignal to the remote toll office.

' When ground is removed from conductor 535, relay 539 operates andextends conductor 535 and the outpulsingcircuit to the outpulse steeringcircuit 540 which controls the transmission of the wanted line number toY the distant olce. Whcn outpulsing has jbeen completed relay Stil isreleased and the talking circuit and the supervisory signalling circuitare cut through to the next otlice.

lf relay 536 is not operated, the operation ot relay 531 connects thepulse generator S29, conductor 535 and the outpulsing circuit over frontcontacts of relay 531 and then over the back contacts of relay 536directly to the outpulse steering circuit Sell. It relay 537 is operatedto prevent the operation of relay 536, it also controls the outpulsesteering circuit to skip the neccessary digits as previously indicated.

The circuits shown in FIGS. 6 and 7 are those required intheAterminating oiilice for a data call. The trunk circuit and registerlink of FIG. 6 are of standard design, but have access only to specialincoming registers, as shown in FlG. 7, which are designed for handlingdata calls.

When a data c all reaches the trunk of FIG. 6, a bridge located in asender at a distant oi'llce, is connected across incoming conductorstlt) and 691, completing a circuit from battery, through the lowerwindingrot relay 603, hack contact of relay 662, conductor 600, throughthe bridge at the distant office, conductor 601, back Contact ot relay602, to ground through the upper winding of relay 663. Relay 693operates in this circuit and closes a circuit from battery, throughresistor 696, back contact ofrelay 6i2, front contact of relay 633, backcontact of relay 6ti2'to the start conductor 5M of the special registerlink V665, operating the register link to connect the trunk o2 FIG. 6Vwith the incominty register of FIG. 7. When the link 605 has operated,conductor 761 is grounded and relay 7h@ is operated in the register,holding the link operated under the control ot the register. With theVVlink 695 operated, the identity of the trunk is passed to the registerby selectively grounding conductors in cable 702 in accordance with thetrunk number and thereby operating the trunk number register 703. Thisprocedure is more fully described in the Busch patent identilied above.When the trunk number has been registered, relay 704 is operated overthe back contact of relay '705. With relay 764 operated, a circuit iSclosed from ground through the winding of relay 706, front contact ofrelay 7b4, conductor 7e?, through the link 605 to battery through thewinding of relay 602. Relay 662 operates in this circuit, disconnectingrelay 663 from the trunk conductors 600 and 601, and connecting groundto conductor 507, which extends through the link 695 to conductor 76Sand the winding of relay 769 to indicateto the register that it mayproceed. Relay 706 also operates in series with relay 602 and locks tocon'- ductor 707, independent Vof: relay 704.

When the llnkihas operated, conductor Gilt) is extended through the linkto conductor 7M), back to contact of relay Y '712 to ground andconductor 691 is extended through the 713 operates in this circuit andprepares the register for receiving the called number.

It will be noted that the connections of battery and ground provided bythe register are reversed from those provided by the trunk. The bridgeacross conductors 6313 and 601 is located in a sender at theintermediate office. which recognizes this battery and ground reversalas a signal that it may proceed to transmit the called number. Thecalled number as transmitted over conductors 66) and 661 is registeredin the called number register 714. When the intermediate oiice hasinished sending the called number, the talking and signaling circuitsare completed through that ofllce, so that the register of FIG. 7 is nowconnected over the talking and signaling circuits with the tandem senderof FIG. 4.

When the called number register 714 has been operated, relay 715 isoperated, transferring the talking conductors 710 and 711 from callednumber register 714 to calling number register 716. 1n addition, relay715 closes a circuit for operating timed pulse circuit 717. This timedpulse circuit 717 first measures a time interval to permit theintermediate office to establish the talking and signaling circuits andto release its sender. The timing circuit 717 then operates to releaserelay 712 to transmit a timed reverse battery signal to the outgoingtrunk at the intermediate oflice, from which it is transmitted over thesignaling path through the intermediate oices to the sender at thetandem ofce.

At the special tandem sender in the tandem office of FIG. 4, relay 428responds to this signal by closing its right contact. When relay 428closes its right contact, it completes a circuit over that contact,front contact of relay 430, back contact of relay 436 to battery throughthe winding of relay 435. Relay 435 operates and locks through thewinding of relay 436 to oil-normal ground, relay 436 remainingunoperated until relay 428 opens its right contact. Relay 435 alsoprepares the outpulse Steering circuit 432 for operation. v When thereverse battery signal ends, relay 4261 closes its left contact,completing a circuit from ground over that contact, back contact ofrelay 434, front contact of relay 435, front contact of relay 431 to thepulse generator 433. The irst ground pulse over conductor 44d operatesrelay 437, followed by relay 438, to transmit the start pulse to theterminating oice. With relay 431 operated, the second pulse on conductor441B is transmitted over front contact of relay 433, front contact ofrelay .431 to the outpulse steering circuit, omitting the data pulse.With relay 431 operated, the control of the digits to be outpulsed istransferred from the called number register 405 to the area code,oi'lice code and calling number registers 425 and 424. When the completecalling number has been transmitted, the outpulse steering circuit 432reoperates relay 443.

At the terminating oiiice register, the complete calling number isreceived and registered by calling number register 716. When theregistration is completed, relay 713 is operated.

In the meantime, the operation of relay '715, in response to thecomplete registration of the called number, operates translatorconnector 719, to connect the called number register 714 with translator720. This translator may conveniently be of the card type employed intoll oices. The card will be selected in accordance with the callednumber and will be punched to register the complete number of thecalling number which is privileged to extend data sending connections tothe data receiving unit identified by the called number. When the numberof the acceptable calling station has been set up in register 721, relay722 is operated. With relays 722 and 718 operated, the matching circuit723 is operated. The calling number automatically derived from the lineitself and registered in register 716 is transferred to the matchingcircuit 723, as well as the calling number indicated by the translatoras acceptable by the called data unit.

CII

Matching circuits of this type are used in toll oi`n`ces, such asdisclosed in the above-identified Gooderham et al. patent, for area codematching and in tandem oices, such as disclosed in the above-identitiedBreed et al. patent for identifying lines requiring service observation.

1f the two calling numbers are the same, match relay 724 is operated. Ifthe two calling numbers are not the same no-match relay 725 is operated.

Assuming the two numbers match, relay 724 closes a circuit from groundover its front contact, back contact of relay 727 to battery through thewinding of relay 712, operating relay 712 to send a reverse batterysignal to the tandem oice. At the same time, relay 724 starts timer 726,which, after an appropriate interval, operates relay 727. Relay 727opens the circuit of relay 712, to terminate the reverse battery signal.

Since the operation of relay 724 indicates that it is permissible tocomplete the connection, relay 724 also operates marker start relay 728.With relay 728 operated, marker connector 729 connects an idle marker730 with the register and the marker proceeds to set up the connectionwith the data receiving station identified by the called number asregistered in register 714. Relay 728 also operates relay 705, openingthe circuit of relay 704, causing the latter relay to release. Withrelay 704 released, ground is connected over conductor 732, through theregister link 605 to battery through the winding of 66S. Relay 608operates in this circuit and, at its front contacts, connects relay 663to conductors 666 and 601, causing relay 603 to reoperate. With relay693 reoperated, relay 6533 locks over a circuit extending from batterythrough the winding of relay 6198, front contact of relay 6412, frontcontact of relay 603, a second front contact of relay 662, to ground ata front contact of relay 608. Relay 60S also provides a holding circuitfor relay 602 so that the latter relay remains operated after theregister is disconnected, which takes place after the marker hascompleted the desired connection and operates the release relay 731.

At the tandem oicc, the reverse battery signal transmitted under thecontrol of the match relay 724 causes relay 42to close its rightcontact, completing a circuit from ground over the right contact ofrelay 428, front contact of relay 43), front contact of relay 436 tobattery through the winding of relay 434. Relay 434 operates in thiscircuit, locks to off-normal ground and closes a circuit for startingthe operation of timer 444, which measures a time interval longer thanthat measured by timer 726 at the terminating ofiice before operatingrelay 44S.

When the reverse battery signal is removed under the control of timer726, relay 428 closes its left contact and, with relay 445 not operated,completes a circuit from ground through left contact of relay 428, frontcontact of relay 434, back contact of relay 445, front contact of relay431, front contact of relay 443 to battery through the winding of relay447. Relay 447 operates in this circuit and connects ground to conductor412, which extends through the sender connector 393 to conductor 312 andbattery through the winding of relay 39S. Relay 3dS operates, in turnoperating relay 362. Relay 3132 closes a circuit from ground over theback contact of relay 3136, front contact of relay 303, front contact ofrelay 302, conductor 311i, through connector 308 to conductor 410 andbattery through the winding of relay 461. Relay 431 operates, openingthe circuit of relay 303 and causing that relay to release. Theoperation of relay 302 and the release of relay 363 disconnects incomingconductors 391i and 361 from the sender and extends them through theleft windings of repeating coils 317 to the windings of relay 3134,which noW reoperates. Relay 304, reoperated, provides a locking circuitfor relay 305. When relay 303 releases a circuit is closed from groundover front Contact of relay 362i, back contact of relay 303 to batterythrough the Winding of relay 396. Relay 306 operates and locks under thecontrol of relay 302, which is in turn held operated under the controlof relay 395. The release of relay 333 disconnects groundfrom thecircuit of relay Lidl in the sender, permitting that relay to release.Relay 36S, in operating, opened the start circuit for the connector 3%,to prevent its reclosure whenv relayV 364 reoperates and relay 303releases. Relay 302, when operated, cormects supervisory relay 320throughthe right windings of repeating coil 317 to outgoing conductors315 and 316. 'Ihe sender and Vsender connector are restored Yto normalin the usual manner. Y

p It the two calling numbers presented to the matching circuit 723 donot match, no-match relay 7 25 is operated as previously stated.Withvrelay 725 operated, ground is connected to the winding of relay712'to cause a prolonged reverse" battery signal to be transmitted tothe tandem sender. Relay 725 also operates the trouble release relay 729which brings about the release ofL the register.

At the tandem sender, this prolonged reverse battery signal causes relay428 to close its right contact, operating relay 434 as previouslydescribed. Relay 434 also starts timer 444 which operates relay 445.With relay 445 operated, the locking circuit for relay 434 is extendedto battery through the winding ot relay 445. With relay 446 operated,the marker connector 407 is operated, connecting an idle marker with thetandem sender, and the marker is'given an indication that it is tormakea trouble record of the call Vand cause a signal to be transmitted tothe calling line that Vthe connection cannot becompleted.

For convenience, the circuits have been shown as relating Yto accessfrom a single calling line. However, if it were desired to give a numberof calling lines access to a particular called line, an arrangementsimilar to the ,card-to-card operation described in the above-identifiedGooderham et al. patent might readily be used. The translator 72th wouldbe provided with a card for each acceptable calling line. The card iirstselected might well be the one carrying thedesignation of the callingline making the greatest use of the called equipment. In any event, theiirst card would carry an indication that a plurality of cards areavailable and, if there were no match, would start a chain operation bywhich each ofthe cards would be selected, one after the other. A matchon any card would immediately operate match relay 724. The last card ofthe group would carry the no-match indication to operate no-match relay725. Intermediate cards would carry an indication which would controlthe chain Operation.

t It will therefore be apparent that the present invention providesmeans for positively preventing the completion of an unauthorizedconnection with the data receiving unit. While the operations `havebeen, for convenience, described as relating to data transmission, itwill be apparent that they are equally'useful whenever itwould beVdesirable to give only limited access to a particular line.

VI claim; `1. In a telephone switching system, subscriber stationshaving unique designations, each comprising a group of decimal digits,switching equipemnt adapted to be controlledby a dialed or keyeddesignation for connecting a calling station with a called station,means in the switchwing equipment having access toY said calling stationto identify and register the designation of said calling station,

. control means serving the switching equipment having Y i access tosaid called station, means to record in said control means thedesignation of a station'authorized to be connected with said called.station, means to transmit the called station Vdesignation and theidentified calling station designation to `said control means,translator means 2. In a telephone switching system, subscriber stationshaving unique designations, each comprising a group ot decimal digits,switching equipment controlled by a dialed or keyed designation forconnecting a calling station with a called station, means in theswitching equipment having access to said calling station to identifyand register the designation of said calling station, control meansserving the switching equipment having access to said called station,means to record in said control means the designations of one or morestations authorized to be connected with said called stat-ion, means totransmit the called station designation and the identified callingstation designation to said control means, translator means accessibleto said control means and means under the control of said translatormeansto cause said last-mentioned switching equipment to complete theconnection of said calling station withrsaidV called station effectiveonly if said identified calling station designation is the same as anyone of said authorized station designations.

3. In a telephone or data switching system, subscriber stations havingunique designations, each comprising a group ot'decimal digits,switching equipemnt controlled by a dialed or keyed designation forconnecting a callling station with a called station, means in theswitching equipment having access to said calling station to identifyand register the designation of said calling station, control meansserving the switching equipment having access to said called station,means to record in said control means theV designation of a stationauthorized to be connected with said called station, means to transmitthe called station designation and the identified calling stationdesignation to said control means, means to record said called stationdesignation and said identified calling station designation in saidcontrol means, matching means accessible to said control means, means totransmit said` identified calling station designation to said matchingmeans, means under the control of said recorded called stationdesignation to transmit the authorized station designation Vto saidmatching means, and means under the conrol of said matching means tocause said last-mentioned switching equipment to complete the connectionof said calling stationwith said called station effective only if saididentified calling station designation is the same as said authorizedstation designation.

4. ln, a telephone switching system, subscriber stations having uniquedesignations each comprising a group of decimal digits, switchingequipment controlled by a dialed or keyed designation for connecting acalling station with a called station, means in the switching equipmenthaving access to said calling .station to identify and register thedesignation of'said calling station, control means serving the switchingequipment having access to said called station, means in said controlmeans to record the designations of a plurality of stations authorizedto be connected with said called station, means in said control means toregister said called station designation and said identified callingstation designation when transmitted thereto, matching means accessibleto said control means, means to transfer said identified calling stationdesignation to said matching means, means underthe control of saidregistered called station designation to transfer said authorizedstation designations, one at a time, to said matching means, and meansunder the control of said matching means to cause said switchingequipment to complete the connection of said calling station with saidcalled station effective only if said identitied calling stationdesignation is the same as any one of said authorized stationdesignations.

5. In a ,telephone switching system, Vsubscriber sta and register thedesignation of said calling station, con-` trol means serving theswitching equipment having access to said called station, means tovrecord the designations of a plurality of stations authorized to beconnected with said called station, means in said control means toregister said called station designation and said identified callingstation designation when transmitted thereto, matching means accessibleto said control means, means to transfer said identified calling stationdesignation to said matching means, means under the control of saidregistered called station designation to transfer' said authorizedstation designations, one at a time, Vto said matching means, and meansunder the control of said matching means for disconnecting al1 of saidswitching equipment from said calling station if said identied callingstation designation is not the same as any one of said authorizedstation designations.

6. In a telephone switching system, subscriber Vstatio'ns having uniquedesignations each comprising a group of decimal digits, switchingequipment controlled by a dialed or keyed designation for connecting acalling station with a called station, means in the switching equipmenthaving access to said calling station to identify and register thedesignation of said calling station, a tandem oice through which theconnections between said calling station and said called station isdirected, means in said tandem ofrice to store said identied callingline designation, control means serving `the switching equipment havingaccess to said called station, means in said control means to recor-dthe designation of a plurality of stations authorized to be connectedwith said called station, means in said control means to register saidcalled station designation and transmit a signal to said tandem oftice,to cause said tandem office to transmit said stored calling linedesignation to said control means, matching means accessible to saidcontrol means, means to transfer said identified calling stationdesignation to said matching means, means under the control of Saidregistered called station designation to transfer the designations ofsaid authorized stations, one at a time, to said matching means, andmeans under the control of said matching means to cause said switchingequipment t0 complete the connection of said calling station with saidcalled station effective only if said identified calling stationdesignation is the same as any one of said authorized stationdesignations.

References Cited bythe Examiner UNITED STATES PATENTS 1,492,995 5/ 24Lubberger 179-18 2,352,492 6/44 Ostline 1797.1 2,402,700 6/46 Williams179-7.1 2,918,553 12/59 Leonard et al 179-18 3,025,367 -3/62 J'acobittiet al L--- 179-1'8 ROBERT H. ROSE, Primary Examiner.

WALTER L. LYNDE, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE 0F CGRRECTION Patent No 3, 189687 June l5, 19

Charles G. Miller It is hereby certified that error appears in the abovenumbered patent requiring correction and that the said Letters Patentshould read as corrected below.

Column l, line 22, for "designations" read designator column 7, line 35,strike out "to"; line 53, for "distance read distant column 8, line 72,strike out "to", seconc occurrence; column 9, line 57, for "713" read718 column 10, line 69, for "poils" read coil column ll, 1i 58 andcolumn l2, line 22, for "equipemnt", each occurrence, read equipmentSigned and sealed this 30th day of November 1965.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

1. IN A TELEPHONE SWITCHING SYSTEM, SUBSCRIBER STATIONS HAVING UNIQUEDESIGNATIONS, EACH COMPRISING A GROUP OF DECIMAL DIGITS, SWITCHINGEQUIPMENT ADAPTED TO BE CONTROLLED BY A DIALED OR KEYED DESIGNATION FORCONNECTING A CALLING STATION WITH A CALLED STATION, MEANS IN THESWITCHING EQUIPMENT HAVING ACCESS TO SAID CALLING STATION TO IDENTIFYAND REGISTER THE DESIGNATION OF SAID CALLING STATION, CONTROL MEANSSERVING THE SWITCHING EQUIPMENT HAVING ACCESS TO SAID CALLED STATION,MEANS TO RECORD IN SAID CONTROL MEANS THE DESIGNATION OF A STATIONAUTHORIZED TO BE CONNECTED WITH SAID CALLED STATION, MEANS TO TRANSMITTHE CALLED STATION DESIGNATION AND THE IDENTIFIED CALLING STATIONDESIGNATION TO SAID CONTROL MEANS, TRANSLATOR MEANS ACCESSIBLE TO SAIDCONTROL MEANS AND MEANS UNDER THE CONTROL OF SAID TRANSLATOR MEANS TOCAUSE SAID LAST MENTIONED SWITCHING EQUIPMENT TO COMPLETE THE CONNECTIONOF SAID CALLING STATION WITH SAID CALLED STATION EFFECTIVE ONLY IF SAIDIDENTIFIED CALLING STATION DESIGNATION IS THE SAME AS SAID AUTHORIZEDSTATION DESIGNATION.